1. Field of the Invention
This invention relates to a video camera system and is suitably applied to the automonous target tracking apparatus in which the field of view of a video camera can track the center of the object, such as a human face model.
2. Description of the Related Art
Heretofore, for an autonomous target tracking apparatus of a video camera, a first automonous target tracking method which memorizes the peak value of high frequency element of brightness signal in the measuring frame and automatically tracks its movement as the feature of the target has been proposed.
Moreover, a second automonous target tracking method, regarding brightness signals of the front and back fields in the measuring frame, whereby a motion vector is formed by taking the key point matching and assuming that the motion vector in the measuring frame represents the movement of the target, has been proposed.
The first automonous tracking method has an advantage that the general construction is simple, but for example, in the case where there is a background tree with a man in the measuring frame, the man cannot be tracked automatically since high frequency element of the tree is the biggest peak at this point.
Furthermore, because basically the first automonous tracking method basically utilizes peak signals, it is easily affected by noise and as a result, there is a possibility that automatic tracking cannot be performed in the photographic environment with low brightness. Also, it is possible that the object with poor contrast cannot automatically be tracked because a high frequency element cannot be extracted.
Furthermore, according to the second automonous tracking method, it is difficult to distinguish whether the calculated motion vector is caused by unintentional movement of hands of video camera or the movement of the object, and in practice there is a possibility that it functions erroneously.